1. Mitosis & Cell Division

2. Centrioles Nuclear envelope Chromatin Interphase -Cell Grows -Genetic Material Replicates -Errors are corrected INTERPHASE

3. Mitosis Mitosis A continuous process that is divided into four stages: A continuous process that is divided into four stages: –Prophase, –Metaphase, –Anaphase, –Telophase The end of Mitosis is marked by the separation of the sister chromatids, forming two nuclei that include a copy of each chromosome The end of Mitosis is marked by the separation of the sister chromatids, forming two nuclei that include a copy of each chromosome

4. Prophase Nuclear envelope begins to break down Nuclear envelope begins to break down Chromosomes condense and become visible Chromosomes condense and become visible Microtubules form around nucleus Microtubules form around nucleus Centrioles segregate to opposite ends of the cell Centrioles segregate to opposite ends of the cell Towards the end of this phase, the microtubules attach to the centromere of the chromatids. Towards the end of this phase, the microtubules attach to the centromere of the chromatids.

5. Prophase Prophase in Onion Root Tip

6. Metaphase Sister chromatids begin to line up towards the middle of the cell forming the metephase plate Sister chromatids begin to line up towards the middle of the cell forming the metephase plate  The metephase plate lines up perpendicular to the spindles such that each new nuclei ends up with one copy of each chromosome

7. Metaphase Metaphase in Onion Root Tip

8. Anaphase Beginning of chromosome segregation Beginning of chromosome segregation –Proteins break down centromeres –Motor proteins begin to move chromosomes to opposite ends of the cell If there are errors during this stage, the chromosomes do not separate equally, causing aneuploid cells. If there are errors during this stage, the chromosomes do not separate equally, causing aneuploid cells. –One nucleus has a greater number of chromosomes than the other. Q: Why do you think this may be harmful to the organism?

9. Anaphase Anaphase in Onion Root Tip

10. Telophase Chromosomes begin to expand and are no longer visible Chromosomes begin to expand and are no longer visible The nuclear envelope begins to reform, creating two nuclei The nuclear envelope begins to reform, creating two nuclei TelophaseTelophase in Onion Root Tip

11. Cytokinesis The plasma membrane begins to squeeze between the two newly formed nuclei The plasma membrane begins to squeeze between the two newly formed nuclei The cell is divided into two The cell is divided into two If the cell has a cell wall, vesicles with cellulose surround the nuclei If the cell has a cell wall, vesicles with cellulose surround the nuclei –The vesicles fuse to create the new plasma membrane –The cellulose inside the vesicles then extend the cell wall. The new cells now enter G 1 The new cells now enter G 1

12. Cytokinesis in Animal Cell Cytokinesis in Plant Cell

13. References http://www.biology.arizona.edu/cell_bio/tutorials/cell_cy cle/cells3.html http://www.biology.arizona.edu/cell_bio/tutorials/cell_cy cle/cells3.html http://www.biology.arizona.edu/cell_bio/tutorials/cell_cy cle/cells3.html http://www.biology.arizona.edu/cell_bio/tutorials/cell_cy cle/cells3.html http://www.botany.org/plantimages/Mitosis.php http://www.botany.org/plantimages/Mitosis.php http://www.botany.org/plantimages/Mitosis.php BSCS Biology: A Molecular Approach (8 th ed.). (2001). Columbus, OH: Glencoe/McGraw-Hill BSCS Biology: A Molecular Approach (8 th ed.). (2001). Columbus, OH: Glencoe/McGraw-Hill Cooper, G. M. (2000). The Cell: A Molecular Approach (2 nd ed). Washington, DC: ASM Press Cooper, G. M. (2000). The Cell: A Molecular Approach (2 nd ed). Washington, DC: ASM Press http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory /files/Bio%20101/Bio%20101%20Lectures/Mitosis/mitosi s.htm http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory /files/Bio%20101/Bio%20101%20Lectures/Mitosis/mitosi s.htm http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory /files/Bio%20101/Bio%20101%20Lectures/Mitosis/mitosi s.htm http://faculty.clintoncc.suny.edu/faculty/Michael.Gregory /files/Bio%20101/Bio%20101%20Lectures/Mitosis/mitosi s.htm